Motor-starting system



June 28,1927.

C. A. JOHNSON MOTOR STARTING SYSTEM Filed June 5, 1920 INVENTOR C/arence fZJo/mson WITNESSES:

ATTORNEY Patented June 28, 1927.

entree STATES PATENT OFFICE.

CLARENCE A. JOHNSON, OF LARIMER, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

MOTOR-STARTING SYSTEM.

Application filed June 8,

My invention relates to motor-starting systems and particularly to systems for starting synchronous motors.

One object of my invention is to provide means for starting the motor of a synchronous motor-generator set-in an automatic substation,

Another object of my invention is to provide a synchronous motor-starting system wherein the actuation of the running circuit interrupter is controlled by predeterminedconditions in the field-magnet windings.

Another object of my invention is to provide a system of the above-indicatedchar- 1 acter that. shall have means for precluding connection of a synchronous motor directly to a source of electromotive force of normal value until the'speed of the motor .corre-- spondsto the synchronous speedthat is de-l termined by" the source of electromotivel force.

A further ob cct of my'invention is to prodetermined value ofvidea simple system of the above-indicated i in its' operation. In starting l'elecltromotive' force is ordinarily applied to vcharacterthat shall automatic reliable fh'e' 'aririatur'yzintlings 5 to pjr ecludetthe "flow of ghr'rent jqi excess ve value therein; The= w 4 5 v. i source of reduced electromotive force until the motorattains its synchronous speed and asynchronous motor, a reduced 1 aim is builtup slowly,

1920. Serial No. 386,222.

the field-magnet winding is traversed by relatively small values of direct current until synchronous speed is reached.- lVhen the motor attains synchronous speed, the field-magnet winding of the motor is rotating at a speed corresponding to the synchronousspeed of the motor and, since there is-substantially. no relative movement between the rotating fieldniagnet winding and the magnetic fluxes that traversethe stator of the motor, an alternating electromotive force is no longer induced in the rotating field-magnet winding. As this alternating electromotive force'is gradually reduced to zero, thedirect-connected ex citer builds up and energizes the field-mag net winding by direct current.

In practicing my: invention, I provideia relay in the circuit of the fieldemagnet winding of'the motor that is responsir'e to a predirect current only. hen the motor attains synchronous speed and the exciter builds up to-atpredetermined val ue,the relay becomes energized and serves to completela circuit ito'energi'ze means for connecting the armature windings directly to the source of normal electromotive1force. The connection bf the motor tothe circuit is thus made dependent upon the m0tor actu-.

ally attaining synchronous speed'; since the 1 generator until's'uehconditions obtain. Premature CODDQCtIII of'the motor to the 'cir- 'forc'ej from' which they are to be energized 'If the armature windings ar'e connectedto thel circuit before themotor has attained its synchronous speech-excessive currents will be caused to traverse the windings, and heavy surges will be produced in tl IB ClICUllS- Unit is thereby prevented.

'Z'Inorder that the operation-of the motorgenerator' Fet may be fullyautomatic, the

Ordinarily, a synchronousfmotor has an excite'r' directly "connected thereto for energizing the-field magnet winding'of the, motor. \(Vhile the motor is starting, the rotating magnetic-fluxes, that'are induced by the currents traversing thearma'ture windings of the motor, induce an alternating elec-V tromotive force in of the motor.

ing of the motor is directly connected across the terminals of the exciter generator armature, and the voltage of the exciter generthe field-magnet winding- Since the field-magnet wind-i startingof the motor maybe controlled by some means that is responsive toa predetermined condition.' AY-dro'p-in'potential of a trolley feeder adjaent-to an automatic railway substation'may serve to actuatea relay to start the motor-generator"set to furnish additional energy to the "feeder, a circuit may be completed by'a' float device at a predetermined low level in a reservoir to energize a relay for starting the'motor to operate a pump for refilling the reservoir, or the starting may be controlled by an attendant.

The starting system herein disclosed may thus be .employed in various applications where a synchronous motor is employed and may be'made automatic by theapplication of a relay thereto that is responsive to a predetermined condition, upon the occurrence of which the operation of the motor is desired.

The single figure of the accompanying drawing is a diagrammatic view of an electrical system en'ibodying n'iy invention.

A synchronous motor 1 is adapted to receive energy from a source 2 of elcctroinotive force through a circuit interrupter To provide a reduced electroniolive force for starting the synchronous inotor 1, a plurality of auto-transforn'iers l are employed that are connected between the. armature windings-of the motor and the source of electromotive force 2 by means of two circuit interrupters :3 and 6. The interrupters 5 and 6 are i'nechanicz-illy connected and are simultaneously actuated. The field-magnet winding 7 of the motor 1 is connected in series with a winding 8 of a direct.current relay 9, across the terminals of'aii exciter generator 1!) that is mechanically connected I to the motor.

The circuit interrupter 3 is provided with a closing magnet 11, a tripping magnet 12 and an auxiliary pallet switch 13. The starting interrupters 1') and (i are provided with a closing magnet 14, a trippinginagnet 15 and an auxiliary pallet switch 16. A control relay 17 is provided with a winding 18 that is responsive toa predetermined voltage on a.trolley feederconductor 19 which is sup plied with energy from a generator 20 that is driven by thesynchronous motor 1.

plurality of contact members 21 of the controlfrelay l7 serve to complete a circuit. for energizing the closing magnet 14 of the starting interrupters 5 and (i. A manuallyoperated switch 22 ,isconnected in parallelrelation with the contact members 21 of the ,control relay 17 and serves as a manuallyoperated means for starting the motor. Two

additional nianually-operated switches 23 and 2 1 may be employed for manually triprnpters'6 and respectively., The relay 9 is provided with a plurality of contact members 25 that are adapted, upon the eiiergiza- 'tion of the relay, to complete a plurality of circuits for energizing the tripping magnet 15 of the interrupters 5 and (S and the closang magnet 11 of the interrupter 3 from a value, engagement is'eflected between the.

contact members 21 of the relay 17, a cir- Y cuit is completed thereby from a conductor 27 of the circuit 26 through the winding of the closing magnet 14 of the interrupters 5 and (3 and through the contact members 29 of the pallet switch 13 of the interrupter Bto the conductor 28 of the circuit 26. The closing magnet 14 is thereupon energized,

gization of the field-magnet winding the direct current from the exciter generator and the interrupters 5 and 6, being mechanically interlocked, are siii'iultaneously closed. When the interrupters 5 and 6' are closed, an electroniotive force is impressed upon the armature windings of the n'iotorl that pro duces' a iotatin'g'inagnetic field which starts the'inotor. Sin'ce the"field-iriagnetwinding 7 of the notoi l is close-circuited through the winding 8 of the relay 9 and the armature windings ofthe direct-connected exciter generator 10, and, since the exciter voltage builds up slowly, insuflicicnt. direct current will traverse'the winding 8 to operate the relay 9 until after the 'inotor 1 has accelerated to synchronous speed. Upon the ener- -pleted, one serving to'energize theclosing magnet 11 of the running interrupter 3 and the-other serving to energize the tripping magnet- 15 of the starting interrupters 5 and 6. The armature windings aresthen directly connected .to the conductors of the circuit 2 by means oftl ie interrupter 3 and have the iull voltage, of the.: circuit i9 impressed thereupon. Since the motor has already attained its synchronous speed, no serious surges are occasioned by c oi'inecting the motor .winding sto' the-circuit: 2' Since the actuation of the runnin "interrupter-'3 is determined by the enr'giz'ation ofjthe relay 9, the actuation of. which is dependent upon the motor J attaining fits synchronous speed in order that theicitecgeneriifor may build up? to -Y its normal voltage, "jthe'fmotbr is safe guar ded'from nected, tothej circuit 2-:

The fauxriliai'yj lszwitch 13 interrupter 3 i'seinployed; to

interrupter 3 isfinfitsf 'pen 'po tion i fTlie auxiliary switches 13 and '5! P 5 ployed to' provide: i'ixili'a 'yi'nf' for: openingthe circuit' 'o f 'tl i e ivi'n'di'n'gsof their respective 'iijiti 'r iprers iajimdf 6," t

The stopping or the iiiotor"r r i" ay be' 'various'ly controlled and?" ade' depeii'deiitlupo i 'prdeteriiiinedjcoiiditioiis a r n'aiiirer similar to the starting thereof. "That-is, the de- Inn ping the starting and the running inter-.i il l h tlp l d $il fil fi ifif ma'ndfof energy froniithe'generaitorfor' the level of the waterin a res'ervoir' may be used as controlling means for stopping tli motor. Y I, therefore, do not Iim'it'the'a'pplication of my motor-'starting'sys'temto an automatic railway or powersubstation embodying a synchronous"motor-generator set nor do I limit my invention to the particular arrangement disclosed, as various modifications may 50 tion be made therein within the spirit and scope of the invention as set forth inthe appended claims.

I claim'as my invention:

5 1. In a system for starting a synchronous motor provided with a direct-connected exciter generator for energizing the field magnet winding of the motor, the combination with a source of el-cctromotive force In and means for connecting thearmature windings of the motor thereto, of means r'csponsive to the energization ofthemotor field magnet from the generator winding for con- I trolling the connecting means. i5 2. In a system for starting a synchronous motor providing with a mechanically connected exciter generator for energizing the fieldmagnet winding of the motor, the combination with a source of electromotive force and means for connecting thearmature windings of the motorthereto, of a directcurrent relay connected in series circuit with the motor field-magnet winding for control ling the connecting means.

3. In a system for startinga synchronous motor provided with a direct-connected exciter generator normally connected to the field-magnet windings of the motor during the starting period thereof, the combination 2:0 with a source of electromotive' "force and means for connecting the armature windings" of tlie' motor thereto, of a relay inthe circuit the' connecting means.

motor provided 'with a. direct-connected exciter generator normally connected 'to' excite the fieldm'agnet windingoi 'themotor duri fg ti ir rl '.th i bfs' st o 24 9?pit f fid f Qi 'l mean gforconnectmg'th'e rm'aLtu're i'vmdmgs "of a 'motor fiel'd-rna nr'et i'winding' 'for' controlling citer generator normally connected to excite nation with a source of electromotive force and means for connecting the armature windings of the motor thereto, of means responsive to a predetermined value of direct current in the motor field-magnet wind- 56 ings for controlling the connecting means.

6. In a system for starting a synchronous motor provided with a direct-connected exciter generator normally connected to excite the field-magnet winding of the motor, the

' combination with a source of electromotive force and means for connectingthe armature windings of the motor thereto, of means for providing a low starting voltage for the m0- tor and means responsive to the energization of the motor field-magnet windings by such 'erator.

of the field-magnet windings for controlling g inottirfthretio ofuiieansmesponsive to a predetermined" current condition in the 1.

motor providedwith a field-magnet winding and an armature-winding, of a direct-connectedexciter generator, means normally connecting theinotor field-magnet winding to the exciter during the-starting period of the'motor, means for applying starting-and normal operating 'volta'ges to-the -motor armature winding, and means in circuit with the motor field-inagnetwinding for controlling the voltage-applying means, said controlling means being non-responsive to the alternating forces inducecl'in the field-magnetwinding by transformer action from-the armature winding and responsive to: a predetermined value of dirmt'current caused-to traverse the field magnet winding by the excitr gen- '8; The combination with a synchronous motor provided with n d1rect-connected exciter generator normally --'connected to :ex-

cite thefield-magnet Winding -of the-motor,

a source of electroii'iotive'force,' a Ecircuit interrupter for connecting-the 'motor armaturewindlngs 'directly-thereto, and: a

plurality of circuit interrupters-for alsoconnecting said armature" windingsthereto 90 through a plurality of transformers: to 1 provide' 'a'reduced voltage rforlstarting the motor,

said interruptersdieing :so interlocked that Y I "saidj'arrnature windlngsmust befirst con- 35 Ina systemfor starting a synchronous nected to the source 0f 'elctromotive: force" "through the *transfohinersfiof meansirespon- 'sive to the" en ergizatiom of'the :motor: field- 'rnagnet wihding liy th'e ex'citen geiieratori for actuating the first mentioned sintenruptenand for simultaneously tripping the starting 'in--' F terrupters. A .L'Ei'ifi? ain;

9." In a system 'for Startiiigva synchronous in'iotonpr'ov ided Y with 'al difect-eonnectedeexciter generator iiormal'ly connec ted 1 to! excite the field-magnet winding-:ofathezmotonl .the' -d l0 combination-with an interrupterifon connectrectly "tofan electric circuit and. a.- .plurality of the field windings of the motor, the combi- I interrupters: for ="eonne'cting gsaid: fax-mature windings to the circuit through a plurality of transformers, of means for so interlocking the interrupters that the firstanentioned interrupter may be actuated only after the plurality of interrupters have been actuated to connect said armature windings to the circuit through the transformers, and means responsive to the energization of the motor field-magnet windings by said exciter generator at synchronous speed for actuating the direct-connecting interrupter.

10 The method of starting a synchronous motor provided with a. direct-connected exciter generator normally connected to the field-magnet winding of the motor to energize the same, which consists in connecting lit) - electromotive force,

the armature windings of the motor to a source of reduced voltage and thereafter connecting said armature windings to the normal operating voltage .whenithe motor field-magnet winding is energized with direct current of a predetermined value from the exciter generator and at a predetermined motor speed.

11. The method of starting-a synchronous 'motor provided with a direct-connected exciter generator normally connected to energize the field-magnet winding of the motor, which consists in connecting the armature windings of the motor to a source of reduced voltage and thereafter connecting said armature windings to the normal operating voltage at a predetermined value of the direct current inthe motor field-magnet winding corresponding to a predetermined motor speed.

12. In a system for starting a synchronous-motor provided with a direct-connected exciter generator. normally connected in circuit with the tield'magnet winding of the motor, the combination with a sourcevof reduced electromotive force, a-.s0urce of electromotive force of normal operating value and means for connecting the armature windings .of the motor thereto, of means for automatically, effect-ing the connection of said armature windings to. the source of reduced circuit. with the motorfield-magnet winding andiactuated after the-motor attains synchronous speed for automatically; effecting the.

disconnection .of said-armature -w-indings from the source of reduced electromotive force and for subsequently-effecting; the connection of said armature-windings-to the source of electromotiveforce of; normal oper-' ating value.

.13; ZDhe. combination Witlizitsynchronous motorprovided with 1 ail-armatureAVInding,

.a fieldmagnet .windingand a =directconnected exciter normallyconnected tosaid tield- :magnet winding, of meansfor consecutively applyingstartingand normahvoltages to the motor. armature winding and a single means depending upon the motor attaining synand means connected in chronous speed and the current supplied to the motor field-magnet winding by the exciter being at least a. predetermined.minimum value, forcontrolling the voltage-applying means.

14. In combination, a source of alternating current, an alternating-current dynamoelectric machine having an armature \vinding and field winding, switching means arranged to connect said armature winding to said source whereby a low voltage is impressed thercon, switching means arranged to connect said armature winding to said source whereby a high voltage is impressed thereon, means adapted. when operated, to effect the operation of saidfirst mentioned switching means, means arranged to supply direct current to said .field winding after theoperation ofsaid first mentioned switching means, and means responsive to the cur rent-through said. field winding to. efi'ect the operation of said second mentioned switching means.

15. In combination, a. Source of alternating current, .an alternating-current dynamoclectric machine having an armature winding a'nda field ,winding,switching means arranged toconnect said armature winding to said source,wherebyalow voltageis impressed thereon, switching means arranged to connect saidarmature winding to' said source whereby. a .high voltagelisl impressed thereon.-meansadapted, when operated, to effect the operation ofsaid tirstmen'tioned switchin 1neans,,.means :arrangcdto supply termined amount .of direct. current throrigh said fieldwinding to efi'ect the operation of said first. mentioned switching nieansf toldis connect said ,armature winding from said source and the operation of said secondmentioned switchingmeans to con'nect'sai'd armature winding to said source.

In testimony whereof,I have. hereunto subscribed my name this 24th day 'of May, 1920.

CLARENCE AcJOHNSOV. 

